Suspended, horizontally extending, drywall ceilings are well known. Such ceilings have wallboard sheets attached by self-tapping screws to rolled T-beams that are suspended from a structural ceiling by hang wires. The T-beams in a horizontal drywall suspended ceiling are united into a horizontal grid of main beams and cross beams, to provide stability. Such a prior art T-beam used in a horizontal suspended drywall ceiling grid is disclosed in U.S. Pat. No. 6,722,098 for Beam for Drywall Ceiling, incorporated herein by reference.
Such a suspended drywall ceiling could be considered a ceiling liner for a structural ceiling.
The prior art T-beams used in such drywall suspended ceilings are continuously formed by passing a web of sheet metal through a series of rollforming stations, as disclosed, for instance, in U.S. Pat. No. 5,979,055, for Process for Producing Rollformed Sections, incorporated herein as reference.
Such T-beams have a cross section of an inverted T shape, with a bulb at the top, a web depending downward from the bulb, and opposing flanges, extending horizontally from the web at the bottom thereof, as seen in the '098 patent. The beam design lends itself to ready insertion of the self-tapping screws into the flanges of the beams.
Such a T-beam used in a horizontal suspended ceiling is primarily subjected to a load downward from the weight of the ceiling.